Beginner into Micros, etc.

But, I'm unsure where to start. I mean, getting hardware in the micro realm is a matter of chance stops at the Goodwill store or something...plug it in, see if it works, etc. No doubt in areas which have businesses which throw away minis the same is the case. However, it looks as though places like Ebay et al will be my source for such things. I don't know how the hardware follows conventions. I mean, in the micro world, there are a lot of standards: ISA, PCI, VGA, etc...so it makes some parts interchangeable and such. I would imagine when you get into micros and such the parts aren't all that interchangeable, and some are downright nasty to obtain. For example, I was looking at this auction today: http://cgi.ebay.com/aw-cgi/eBayISAPI.dll?ViewItem&item=469865813 It's a VAXstation 3100. I know nothing about it, but that doesn't mean I can't learn. But it looks like it doesn't come with a monitor, keyboard, etc, so I'd have to get those. And, of course, for the life of me I don't know what they take. So, if I were to bid on it, I'd be getting something I didn't know about, get it home, and then watch it collect dust.